Why does my simple poker program continue to draw the same cards?

Question

I'm learning Java for my own and i have this problem:

I created a poker program, and every time, both the AI and I draw nothing but the Ace of Spades (5 each) every round. How can I fix this?

import java.io.IOException;
import java.util.Scanner;

public class poker {
    static Scanner input = new Scanner(System.in);
    public static void main(String[] args) throws IOException {
        int score1 = 0,score2 = 0;
        for (int i=0; i<10; i++) {
            int[][] previous_cards = new int[0][2];
            int[][] hand1 = generate_hand(previous_cards);
            int[][] sorted1 = sort_hand(hand1);
            System.out.println("Round "+(i+1)+": ");
            System.out.print(" Your hand: ");
            print_hand(sorted1);
            int identify_hand1 = identify_hand(sorted1);
            System.out.print(" ");
            print_identify_hand(identify_hand1);
            System.out.println();
            int[][] hand2 = generate_hand(hand1);
            int[][] sorted2 = sort_hand(hand2);
            System.out.print(" Computer hand: ");
            print_hand(sorted2);
            int identify_hand2 = identify_hand(sorted2);
            System.out.print(" ");
            print_identify_hand(identify_hand2);
            System.out.println();
            int compared = compare_hands(sorted1,sorted2);
            if (compared==-1)
                System.out.println(" You win this round!");
            else if (compared==1)
                System.out.println(" The computer wins this round!");
            else System.out.println("Draw!");
            score1 += (compared<0)?1:0;
            score2 += (compared>0)?1:0;
            System.out.println(" Score: You:"+score1+" - Computer:"+score2);
            input.nextLine();
        }
        if (score1<score2)
            System.out.println("The computer won with: "+score2+"-"+score1+".");
        else if (score1==score2)
            System.out.println("Draw: "+score1+"-"+score2+".");
        else System.out.println("You won with: "+score1+"-"+score2+".");
    }
    public static int[][] generate_hand(int[][] previous_cards) {
        int[][] hand = new int[5][2];
        return hand;
    }
    public static int[] generate_card() {
        int[] card = new int[2];
        card[0] = (int) (Math.random()*13 + 2);
        card[1] = (int) (Math.random()*4 + 1);
        return card;
    }
    public static int compare_2_cards(int[] card1, int[] card2) {
        return 0;
    }
    public static void print_hand(int[][] hand) {
        System.out.print(card_to_String(hand[0])+", ");
        System.out.print(card_to_String(hand[1])+", ");
        System.out.print(card_to_String(hand[2])+", ");
        System.out.print(card_to_String(hand[3])+", ");
        System.out.print(card_to_String(hand[4]));
    }
    public static String card_to_String(int[] c) {
        String card = "";
        if (2<=c[0] && c[0]<=10)
            card += c[0];
        else if (c[0]==11) card += "Jack";
        else if (c[0]==12) card += "Queen";
        else if (c[0]==13) card += "king";
        else card += "Ace";
        card += " of ";
        if (c[1]==1) card += "hearts";
        else if (c[1]==2) card += "diamonds";
        else if (c[1]==2) card += "clubs";
        else card += "spades";
        return card;
    }
    public static int[][] sort_hand(int[][] hand) {
        int[][] sorted = new int[5][2];
        return sorted;
    }
    public static void print_identify_hand(int identify_hand) {
        if (identify_hand==1)
            System.out.print("(straight flush)");
        else if (identify_hand==2)
            System.out.print("(four of a kind)");
        else if (identify_hand==3)
            System.out.print("(full house)");
        else if (identify_hand==3)
            System.out.print("(four of a kind)");
        else if (identify_hand==4)
            System.out.print("(flush)");
        else if (identify_hand==5)
            System.out.print("(straight)");
        else if (identify_hand==6)
            System.out.print("(three of a kind)");
        else if (identify_hand==7)
            System.out.print("(two pairs)");
        else if (identify_hand==8)
            System.out.print("(one pair)");
        else
            System.out.print("(nothing - high hand comparison)");
    }
    public static int compare_hands(int[][] hand1,int[][] hand2) {
// IMPLEMENT: compare 2 cards
        return 1;
    }
    public static int identify_hand(int[][] hand) {
        if (hand[0][1]==hand[1][1] && hand[1][1]==hand[2][1] && hand[2][1]==hand[3][1] && hand[3][1]==hand[4][1] && // compare that they have the same suit
                hand[0][0]+1==hand[1][0] && hand[1][0]+1==hand[2][0] && hand[2][0]+1==hand[3][0] && hand[3][0]+1==hand[4][0]) // compare card numbers
            return 1;
        if (hand[0][0]==hand[1][0] && hand[1][0]==hand[2][0] && hand[2][0]==hand[3][0]) // compare card numbers
            return 2;
        if (hand[1][0]==hand[2][0] && hand[2][0]==hand[3][0] && hand[3][0]==hand[4][0]) // compare card numbers
            return 2;
        return 9;
    }

}

I think you're going to need to learn how to use a debugger. — Fred Larson, Mar 24 '17 at 14:37
`new int[0][2]` can never hold data. Your names violate the Java naming conventions. The answer from @Berger lays out the other empty-array issues. — Lew Bloch, Mar 24 '17 at 15:55

score 3 · Answer 1 · answered Mar 24 '17 at 14:46

Your int[][] hand objects are empty.

The generate_hand method returns an empty array, sort_hand returns another empty array, the other methods don't alter the array at all.

You end up passing empty (for int arrays, that means that each index contains 0) arrays to card_to_String, which then displays the result for c[0] == 0 and c[1] == 0, you got it...this is Ace of spades.

Why does my simple poker program continue to draw the same cards?

1 Answers1